We will study the function and genetics of the Ia and H-2 K/D antigens of the mouse major histocompatibility complex. These will be accomplished by production of a panel of monoclonals all directed at a single H-2 haplotype, combined with production of panels of helper and cytotoxic clones also recognizing the same H-2 molecules. These approaches will allow us to define the portions of Ia and K/D molecules used for recognition by T cells. In addition, we will define restriction fragment length polymorphisms on Chromosome 17 in order to provide both additional genetic markers and reveal the number and position of DNA sequences which are H-2 related. Finally we will determine precisely the role of K/D molecules and their domain by combining the CTL clones and DNA mediated gene transfer.